Satellite-to-satellite handover, with associated changing of antenna pointing from one satellite to another, is used for satellite ground terminals communicating through a Low Earth Orbit (LEO) or Medium Earth orbit (MEO) satellite. The satellite-to-satellite handover may be used for mobile satellite terminals communicating through a Geosynchronous Earth Orbit (GEO) satellite when a terminal can move between coverage areas of two GEO satellites, for example, a terminal on a plane in flight. For a LEO or MEO system terminal, a Very Small Aperture Terminal (VSAT) communicates via a satellite moving in an arc across the sky and eventually beyond a range of the VSAT antenna or link (i.e., waveform). The VSAT maintains communication continuity by switching its antenna and communication path to a different satellite in range. For a GEO system mobile terminal, the terminal moves while the satellite remains effectively in the same orbital location, and as the terminal moves out of the coverage range of a GEO satellite the VSAT maintains continuity of communication by switching its antenna and communication path to a different GEO satellite in coverage range.
In the prior art, such satellite-to-satellite handover has been achieved using a single antenna that is repointed to transition the communication path from one satellite to another. Protocol signaling may be used between the VSAT and a Gateway (GW) to pause traffic during repointing/handover and to exchange handover signaling to avoid packet loss. A satellite system may omit use of such a protocol with consequent packet loss, and possibly with higher layer protocol recovery.
In the prior art, satellite-to-satellite handover has also been achieved using multiple antennas, such that one antenna is pointed at a new satellite while another antenna is pointed at and is in active use for traffic with another satellite. In such configurations, the uplink and downlink communication paths are switched from one antenna to the other at the same time.